docs: def uhs_dt(self):  # used for CSV and NPZ export
          """
          :returns: a composity dtype (poe, imt)
          """
          imts_dt = numpy.dtype([(imt, F32) for imt in self.imtls
                                 if imt.startswith(('PGA', 'SA'))])
          return numpy.dtype([(str(poe), imts_dt) for poe in self.poes])